HD74LS248 Datasheet, PDF (2/7 Pages) Hitachi Semiconductor – BCD-to-Seven-Segment Decoders/Drivers(internal pull-up outputs)

HD74LS248
Function Table
Decimal
or
Function ^{LT RBI}
Inputs
DC
B
BI/
A RBO a
b
Outputs
c
d
e
f
Note
g
0
H
H
L
L
L
L
H
H
H
H
H
H
H
L
1
H
X
L
L
L
H
H
L
HH
L
L
L
L
2
H
X
L
L
H
L
H
H
H
L
H
H
L
H
3
H
X
L
LHH H
HHHH
L
L
H
4
H
X
LHL
L
H
L
HH
L
L
H
H
5
H
X
L
H
L
H
H
H
L
H
H
L
H
H
6
H
X
L
HH
L
H
H
L
H
H
H
H
H
7
H
X
LHHH H
HHH
L
L
L
L
1
8
H
X
H
L
L
L
H
H
H
H
H
H
H
H
9
H
X
H
L
L
H
H
H
H
H
H
L
H
H
10
H
X
HLHL
H
L
L
L
HH
L
H
11
H
X
HLHH H
L
L
HH
L
L
H
12
H
X
HH L
L
H
L
H
L
L
L
H
H
13
H
X
HHLH H
H
L
L
H
L
H
H
14
H
X
HHH L
H
L
L
L
HHH
H
15
H
X
H
H
H
H
H
L
L
L
L
L
L
L
BI
X
X
X
X
X
X
L
L
L
L
L
L
L
L
2
RBI
H
L
L
L
L
L
L
L
L
L
L
L
L
L
3
LT
L
X
X
X
X
X
H
H
H
H
H
H
H
H
4
H; high level, L; low level, X; irrelevant
Notes: 1. The blanking input (BI) must be open or held at a high logic level when output functions 0 through 15 are
desired. The ripple-blanking input (RBI) must be open or high if blanking of a decimal zero is not desired.
2. When a low logic level is applied directly to the blanking input (BI), all segment outputs are off regardless of
the level of any other input.
3. When ripple-blanking input (RBI) and inputs A, B, C, and D are a low level with the lamp test input high, all
segment outputs go off and the ripple-blanking output (RBO) goes to a low level (response condition).
4. When a blanking input ripple blanking input (BI/RBO) is open or held high and a low is applied to the lamp-
test input, all segment outputs are on.
Rev.3.00, Jul.15.2005, page 2 of 6